1. Field of the Invention
The present invention relates to disk drives of the type that accept removable disk cartridges, and more particularly, to a disk drive having a mechanism for automatically loading a spindle motor, i.e., moving the spindle motor into engagement with the hub of a disk cartridge upon insertion of the disk cartridge into the drive.
2. Description of the Prior Art
Removable disk cartridges for storing digital electronic information typically comprise an outer casing or shell that houses a rotatable recording medium, or disk, upon which electronic information can be stored. The cartridge shell often comprises upper and lower halves that are joined together to house the disk. The disk is mounted on a hub that rotates freely within the cartridge. When the cartridge is inserted into a disk drive, a motor-driven spindle in the drive must engage the hub in order to rotate the disk(s) within the cartridge.
Standard floppy disk drives typically employ a mechanism that guides the disk cartridge as it is inserted into the drive so that the hub of the disk is brought downwardly into engagement with a fixed, rotatable spindle. These drives must be of sufficient height to accommodate the vertical movement of the floppy disk.
A more preferable solution is to provide a straight insertion path for the cartridge and to move the spindle motor into engagement with the hub of the cartridge. Published International Application No. WO 93/18507, U.S. Pat. No. 5,317,464 (Witt et al.) and U.S. Pat. No. 4,663,677 (Griffith et al.), the latter of which is assigned to the same Assignee as the present invention, all describe removable cartridge disk drives in which the spindle motor is moved vertically into engagement with the hub of a disk cartridge upon insertion of the cartridge into the disk drive. In each case, movement of the spindle motor is effected through a complex series of mechanical linkages. The complexity of such mechanical linkages increases the manufacturing costs of the disk drive. Moreover, each of these prior art disk drives requires manual operation by the user. For example, in both U.S. Pat. No. 4,663,677 and Published International Application No. WO 93/18507, the spindle motor is brought into engagement with the disk cartridge by the manual operation of a lever disposed on the front of the drive chassis. Movement of the lever is translated into movement of the spindle motor by a series of linkages, cams and gears. In U.S. Pat. No. 5,317,464, the manual closure of a drive door is translated through a series of linkages and gears into vertical movement of the spindle motor.
U.S. Pat. No. 4,482,993 discloses a compact disk player that employs a motor driven cam member to move the spindle motor of the drive vertically into engagement with the central hub of a compact disk. The loading mechanism is not designed for use with disk cartridges of the type described above. Rather, the disclosed drive is designed to receive standard compact disks that are not contained within a cartridge housing. An opto-electronic switch detects insertion of a compact disk into the drive and activates the motor driven cam member in order to move the spindle into engagement with the disk hub. As the cam mechanism brings the spindle motor into engagement with the disk hub, the mechanism contacts a mechanical switch that deactivates the cam mechanism. Activation of an ejection button causes the motorized cam mechanism to be reactivated, thereby lowering the spindle motor.
Unfortunately, the mechanism disclosed in the aforementioned patent is bulky and requires the drive to be exceedingly tall in order to accommodate the loading mechanism. Additionally, the drive cannot sense or determine the relative position of the spindle motor or cam member at all times. These and other disadvantages make the loading mechanism of this patent impractical for use in a compact, reduced height disk drive designed for use with removable disk cartridges.
In view of the foregoing, there is a need for an improved spindle motor loading mechanism that is more compact, cost effective and precise, and that does not require manual operation of a lever, or the like, in order to bring the spindle motor into engagement with a disk cartridge. The present invention satisfies this need.